What is the gold-standard fixative for routine immunohistochemistry?
Ihc Fixation Processing Retrieval
Question · Easy
For breast ER, PR, and HER2 testing, what formalin-fixation interval is specified by ASCO/CAP guidance?
Question · Medium
Enzyme label named after a pungent root vegetable that turns chromogens into colored deposits in IHC.
Detection Systems
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Introduction and Exam Overview
1.1 Current QIHC Exam Facts
Study guide
Cold ischemia time refers to:
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Which clearing agent is most commonly used during routine paraffin tissue processing?
Chromogen that forms a brown deposit where peroxidase is present.
Standard section thickness for IHC is:
Which slide type is preferred for IHC to ensure tissue adhesion through retrieval and washes?
Chromogen that gives a red product where peroxidase is present.
1.2 Eligibility, CMP, and How to Use This Guide
What is the general rule for setting the flotation-bath temperature for paraffin sections?
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Term Match
The chemical mechanism of formalin fixation is:
One of the two most common dye labels for antibody-based microscopy, emitting green light.
Heat-induced epitope retrieval (HIER) primarily reverses:
Citrate buffer used for HIER typically has a pH of:
Histopathology's gold-standard fixative for decades, labeled 10% though it holds only 3.7% to 4% formaldehyde in a phosphate solution.
Specimen Handling
Detection Systems: Immunofluorescence, Enzymes, and Chromogens
2.1 Immunofluorescence Detection
Which buffer is the typical high-pH HIER solution?
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Term Pairs
Which HIER method reaches the highest temperature and can use a short hold at its target pressure and temperature?
To encase tissue in paraffin so it can be cut into thin sections.
An example of an enzymatic (proteolytic) retrieval reagent is:
Over-fixation of tissue in formalin most commonly causes:
Kind of section cut on a cryostat for rapid diagnosis during an operation.
2.2 Detection Enzymes
Decalcification of bone for IHC is best performed with:
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Term Search
The purpose of dehydration during paraffin tissue processing is to:
Technique that heats fixed sections in citrate or Tris solution to near or above 100°C to restore antigen binding sites.
Antigen Unmasking
Which storage condition is most likely to cause loss of antigenicity in unstained slides over time?
Which fixative is unsuitable for downstream nucleic acid testing because it degrades DNA/RNA?
Chelating agent used for antigen retrieval at pH 8.0 on its own, or at 0.01 M mixed with 0.1 M Tris at pH 9.0.
2.3 Chromogens and Substrates
If a tissue section detaches during HIER, the most likely root cause is:
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A pathologist requests IHC on a recently received frozen specimen. The first preparation step before IHC should be:
Question · Hard
Approach that uses a digestive enzyme such as trypsin or pepsin to cleave cross-links masking target sites in fixed tissue.
DAB (3,3'-diaminobenzidine) chromogen produces:
Ihc Detection Chromogens
AEC chromogen is unsuitable for permanent slides because it is:
Egg-white protein that binds a vitamin tightly and forms the bridge in one classic signal-amplification method.
Staining
2.4 Dual-Chromogen and Multiplex Detection
Endogenous peroxidase activity is blocked using:
Levamisole is used in IHC to inhibit:
Kind of IHC method in which the primary antibody itself carries the enzyme label.
Which detection system is most susceptible to endogenous biotin background, especially in liver and kidney?
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